What is the role of Islam on environmental conservation?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His Slave and Messenger.

Islam, undoubtedly, takes care of environment by banning any form of harm to it as well as ordering people to protect it. Among the Divine Decrees that aim at maintaining the environment are:
1) Decree against spoiling things on earth. Allaah Says (what means): {And do not do mischief on the earth, after it has been set in order, …} [Quran 7:56].
2) Banning making mischief on earth and destroying crops and progeny, and dispraising those who do such actions. Allaah Says (what means): {And when he turns away (from you "O Muhammad"), his effort in the land is to make mischief therein and to destroy the crops and the cattle, and Allaah likes not mischief.} [Quran 2:205].
In the same vein, Ibn 'Abbaas reported that the Prophet said: "There should be no harm nor reciprocal harm." [Ahmad and Abdur-Razzaaq in his "al-Musannaf"]. In simple words, Islam bans harming others and bans reciprocal harm is also banned.
On the other hand, in Islam the following should be done to protect and preserve the environment:
1) Planting trees, bushes, shrubs, etc. … for the sake of the reward in the Hereafter. Anas reported that the Prophet said: "If a Muslim plants a tree or cultivates a crop, then whenever a bird or a man or an animal eats from it, it will be considered as a charity for him." [Muslim]
2) Imaams al-Bukhari and Muslim reported from Abu Hurayrah that the Prophet said: "There is a reward for service to every living creature."
Generally speaking, in Islam all aspects of the environment are addressed. Agriculture is seriously considered. For example, the Prophet ordered everyone to plant even it is time for judgment: ''If the Hour occurs and one of you holds a seed in his hand, then if he can sow it before the Hour occurs, he should do so.” [Ahmad]
Moreover, Muslims are instructed to cultivate barren lands and for such a task, a good reward is prepared for them in the Hereafter. Imaam Ahmad reported in "al-Musnad" from Jaabir that the Prophet said: "Whoever cultivates a wasteland will be rewarded; whatever is eaten from it (by a living creature) is a charity on his part." [Al-Albaani ruled it to be sound]
Furthermore, Islam urges its followers to keep the streets clean and free from any harm, and such work is considered as a part of faith. Abu Hurayrah reported that the Prophet said: "Al-Eemaan (Faith) consists of more than sixty parts, the best of which is to acknowledge La Ilaaha Illa Allaah (i.e. there is none worthy of worship except Allaah); and the lowest of them is to remove a thing that causes harm from a thoroughfare, and al-Hayaa' (modesty) is also a part of al-Eemaan." [al-Bukhari and Muslim]
Another Hadeeth is cited from Ma'qil Ibn Yasaar who said: I heard Allaah's Messenger saying: "Whoever removes something harmful from the path of Muslims, a good deed will be written for him, and whose good deed is accepted (by Allaah) will enter Paradise." [at-Tabaraani in "al-Mu'jam" and al-Bukhari in "al-'Adab al-Mufrad"]

Besides, At-Tirmithi reported from Abu Hurayrah that the Prophet said: "A man passing along a road found a thorny branch leaning over the road and pushed it away. Allaah appreciated his action and forgave his sins."
As for animals, in Islam all human beings are instructed to safeguard all animals, eatable or not, and states that those who hurt animals will be punished. In a sound Hadeeth:

"A woman was tortured for a cat she imprisoned until it died. She went to hell because of it, having neither fed it nor watered it, for she confined it and would not let it go forage on the small creatures of the earth." [al-Bukhari]

Imaams al-Bukhari and Muslim reported from Ibn 'Umar that the Prophet said: "May Allaah's curse be upon the person who makes a living animal a target for shooting (i.e. for the sake of amusement and sport)".
Also, in Islam, streets, roads and parks, are to be kept safe and clean, and spoilers will face a severe punishment. Abu Hurayrah reported that the Prophet said: "Beware of two cursed practices". The companions said: 'What are the two cursed practices?' The Prophet answered: "A person answering the call of nature in a public thoroughfare or in a shady place (where people rest)." [Muslim]
In addition, in Islam, all human beings are ordered to maintain water. Abu Hurayrah reported that the Prophet said: "Avoid urinating into still water (in a reservoir or pond, i.e. water that does not flow), and then bathing with it."
Needless to say that in Islam spoiling seas with nuclear radiation, destroying extra food fearing low prices, destroying trees and killing animals for amusement and safaris, wasting environmental resources and committing hostile acts against others, are all condemnable acts.

Allaah Knows best.